The present invention relates to power tools for attaching connectors to electrical power distribution lines.
U.S. Pat. No. 4,722,189 assigned to Burndy Corporation is directed to an explosively operated tool for connecting a tap or branch cable to a permanently installed main power cable. The connection between main cable and tap cable is established by means of a C-shaped sleeve joining the spaced tap and main cables and by a wedge driven into the space between the cables within the C-shaped connector sleeve. Strong physical and electrical connections are established by the connector.
The tool disclosed in the '189 patent drives the wedge into the C-shaped sleeve in the space between the main cable and the tap cable as the cable connection is established. The power tool includes an anvil and power ram which engage the connector workpiece and drive the connector wedge into final position. The power tool uses an explosive charge which generates sufficient force to drive the wedge into the sleeve between main cable and tap wire. As disclosed in U.S. Pat. No. 4,722,189, the power tool and cartridge case have interrelted designs and modes of operation for safe operation.
The explosive charge includes a tubular cartridge case, a rim-fire power cell held by a supporting collar, and a power piston for transmitting explosive force to the power ram when operating the power tool. The tubular cartridge is open-ended and the collar positions the rim-fire power cell at the breech end of the cartridge. The power piston is fitted in the cartridge case ahead of the power cell for engagement with the power ram. The subassembly of power piston and power cell with supporting collar are slidably mounted within the cartridge case so that the power cell can be spaced inwardly from the breech end of the cartridge case. In the assembled cartridge case, the power cell is recessed within the case and is inaccessible to a firing pin in order to avoid premature or inadvertent firing until the power tool is armed and manipulated for safe firing by the operator. The cartridge case is loaded into the tool with a safely recessed power cell inaccessible to the firing pin. After inserting the cartridge case into a firing chamber, the tool is further manipulated so that the power ram enters the open muzzle end of the cartridge case, pushes the power piston and power cell to the breech end of the cartridge case bringing the rim-fire power cell within range of the firing pin in ready-to-fire condition. The ready-to-fire condition of the cartridge case occurs as the operator manipulates the power tool and places the anvil and power ram into engagement with a connector workpiece positioned between main and tap cables. As a result of the interrelated design of cartridge case and power tool, the power tool cannot be fired until the operator engages a connector workpiece in the course of establishing the cable interconnection. The tool then is ready to be fired.
If, for some reason, the operator decides not to fire the power cartridge and disengages the power tool from an unfinished workpiece connector, then the cartridge case will remain in the ready-to-fire position and present a hazardous condition if the tool is not immediately used or if the cartridge case is not immediately extracted from the firing chamber. The present invention, therefore, is directed to a safety arrangement by which an explosively operated tool with cartridge case in the ready-to-fire position can be disarmed and returned to a safe (not ready-to-fire) position in the event the operator decides not to fire the tool after arming it and disengages the tool from an unfinished connector workpiece.